Heart valves control the heart function; which is the responsible for blood distribution through the lungs and the body. Modeling valves' function may provide a tool for studying the heart's performance, as well as, it helps to represent some of the most common heart’s abnormalities such as mitral valve regurgitation and aortic stenosis. Cardiovascular system models using electrical systems do not model chambers and the valves are ideal. This study proposes a model for heart valves based on the seven cardiac cycle phases, and representing times and shapes for the three real valve operation stages: opening, slow closing and quick closing. It is possible to simulate different slopes in the systolic and diastolic stages, in addition to their time duration depending on the heart rate. Additionally, one can use parameters to represent different hearts sizes.